Most electrical equipments have an electrical socket for receiving an electrical plug. The electrical plug supplies power to a power supply unit in such an electrical equipment, which in turn supplies power to the electrical components in the equipment. The equipment usually has a housing to house the circuitries of the power supply unit, the electrical connections between power supply unit to the components and the electrical connections among the components.
When there is a fault in the functioning of the electrical equipment, a cover of the housing is typically removed to check whether any of the electrical components are faulty. The checking for faulty components usually includes probing the electrical connections of the components and the circuitries. The circuitries and the electrical connections, especially those at the power supply unit, may carry high voltages from the electrical plug. If the power supply is not turned off, a technician or user may receive an electrical shock while checking for faulty components or when removing the cover of the equipment. Such electrical shocks are hazardous, and may cause burns or even death to the technician or user.
A safety interlock switch is commonly included in the electrical equipment to prevent against such electrical hazards. The safety interlock switch is a mechanical switch which cuts off the power supply from the electrical plug. The switch may be attached to the cover of the equipment, so that the switch is automatically actuated when the cover is removed. However, any accidental activation of the switch while checking for faulty components may make the circuitries and the electrical connections “live”.
In some examples, the power supply unit is enclosed in a protective cage since the circuitries handling the high voltages are usually in the power supply unit. However for some electrical equipment, the electrical connections outside the power supply unit also carry high voltages. In addition, the protective cage may also cause an increase in airflow resistance, and hence, affect the cooling effectiveness of the components in the equipment.